Ammunition cartridge

ABSTRACT

An ammunition cartridge having a bullet with a curved front end terminating in a flat nose normal to the longitudinal axis of the bullet and a casing attached to the rear end of the bullet is disclosed. The nose is provided with a centrally disposed projection and a reservoir of lubricant around the projection.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a U.S. National filing under §371 of InternationalApplication No. PCT/GB02/00057, filed 9 Jan. 2002, claiming priorityfrom British Appln. No. 0100578.4, filed 9 Jan. 2001, now pending (whichis hereby incorporated by reference).

FIELD OF THE INVENTION

This invention relates to ammunition cartridges. It is particularlyconcerned with target and sporting ammunition, especially rimfire .22ammunition, and will be more specifically described below with referenceto .22 ammunition cartridges, although it will be appreciated that it isnot intended to be limited thereto.

BACKGROUND OF THE INVENTION

Conventionally, .22 rimfire ammunition cartridges comprise a cylindricalcasing closed at one end and open at the other, the open end beingcrimped to a bullet, usually of lead. The closed end or head of thecasing defines an annular flange or rim containing a priming compositionwhich ignites by a rimfire strike and the hollow body of the casingcontains a propellant which is fired by the ignition of the primercausing rapid expansion of hot gases to force the bullet from itsseating.

The bullet conventionally has a cylindrical body portion, which may besolid or hollow and a tapered, curved, or so-called ogive, portionleading from the cylindrical body to the nose of the bullet. The bodyportion usually has external knurls to hold lubricant which is providedto prevent material being stripped from the circumference of the bulletas it is expelled along the barrel of the gun.

It has previously been proposed, see for example, U.S. Pat. No.3,866,536, to provide a flat nose on a bullet so that the ogive curve isin effect shortened and cut off at the nose end.

SUMMARY OF THE INVENTION

It is an object of the invention to provide an improved bullet shape toprovide greater accuracy and consistency.

Accordingly, in one aspect, the invention provides an ammunitioncartridge comprising a casing attached to a bullet, the bullet having abody portion of generally cylindrical shape, one end of which isattached to the casing and the other end of which has a tapering curvedportion, the curved portion ending in a flat nose normal to thelongitudinal axis of the bullet and the flat nose having acentrally-disposed projection in the direction of the longitudinal axis.

In another aspect the invention also provides a bullet having the shapedescribed in the immediately preceding paragraph.

The projection from the flat nose of the bullet is preferably circularin plan, although this is not essential. The projection is preferablyuniformly disposed about the longitudinal axis of the bullet to providean even weight distribution and it could, if desired, be for example ofsquare configuration in plan.

Where the projection is circular in plan, it may be of cylindricalconfiguration so as to have a flat outer end or it may be domed so as tohave a curved outer end.

In a yet further aspect, the invention provides an apparatus for themanufacture of a bullet, the apparatus comprising a die, a first part ofwhich defines a cylindrical cavity to receive the material to form thebullet, and two punch parts, one located at each end of the cavitywhereby the material may be compressed in the cavity between the punchparts, the first part of the punch being shaped to define the rearportion of the bullet which is to be attached to a casing and the secondpart of the punch being shaped to have a hollow portion defining thecurved portion and nose of the bullet, the curved portion ending in aflat face with a recess extending from the flat face to define a noseprojection of the bullet.

In a conventional bullet press, the surface defining the cavity in whichthe bullet is formed between the two punch parts has a narrow spruepassageway leading into the cavity. The bullet is, therefore, formedwith a sprue usually at right angles to its longitudinally extendingbody.

In the apparatus of the present invention, however, it is preferred thatthe sprue passageway be provided in the second part of the punch,extending from the recess which defines the nose projection in thegeneral direction of the longitudinal axis of the bullet. If this spruepassageway extends completely through the second part of the punch, i.e.vents through the punch, we have found that improved bullet shape anduniformity with greater conformity to the final desired shape can beobtained.

In a still further aspect, the invention provides a method ofmanufacturing a bullet, the method comprising providing material to formthe bullet, shaping the material to form the bullet characterised inthat a front end of the bullet is formed with a centrally disposedprojection extending from a flat nose in the direction of thelongitudinal axis of the bullet.

Preferably, the method includes forming a reservoir of lubricant on thenose around the projection.

We have surprisingly found that the novel bullet shape of the inventioncan provide increased accuracy and consistency. Although not wishing tobe limited to any particular theory, it is believed that one reason forthe improvement over conventional bullet shapes is to do with thelubrication of the bullet. Bullets of the invention are coated as isconventional by coating with a liquid lubricant which is allowed to seton the outer surface of the bullet. The bullet may have conventionalknurling on its cylindrical outer surface to provide reservoirs of thelubricant but we have found that an additional reservoir of lubricantcan be provided during the coating process at the bullet nose around thebase of the projection from the flat surface. This further reservoir canprovide an extra degree of lubrication on firing of the ammunition sothat the bullet surface is better protected as it travel along thebarrel.

It is also believed that the bullet shape of the invention provides animproved relationship between the centre of gravity and the centre ofpressure of the bullet. The centre of gravity normally lies within thecylindrical body portion of the bullet. The centre of pressure lieswithin the curved portion of the bullet and is the notional point where,when the bullet is fired, the lines of pressure normal to all points onthe outer ogive surface meet inside the bullet. The centre of pressurein a bullet of the invention is moved further away from the centre ofgravity, which is believed to improve balance and ballistic accuracy.

Embodiments of the invention will now be described by way of exampleonly with reference to the accompanying drawings in which: drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a conventional TENEX gullet, which is a high quality .22rifle bullet;

FIG. 2 shows a first bullet of the invention;

FIG. 3 shows a second bullet of the invention;

FIG. 4 shows a third bullet of the invention; and

FIG. 5 shows a die for the manufacture of a bullet of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In FIG. 1 a conventional .22 bullet 10 has a rear cylindrical heelportion 12 with a concave cavity 14 in its rear face 16. A step 18 leadsfrom the front of heel portion 12 to a slightly larger diametercylindrical central body portion 20. At the front of the body portion 20a step 22 leads to the tapered curved or ogive portion 24 at the frontof which is the nose 26.

It will be seen that the ogive portion 24 has a double curvature with afirst region 28 extending from the body portion having a much greaterradius than the front region 30 leading to the nose.

To form the desired 0.22 cartridge a metal casing 32 will be crimped tothe heel portion 12 and then the bullet is coated with a suitablelubricant. The coating and crimping techniques are well known in theart.

In FIG. 2 is shown a first bullet 100 of the invention.

This has a rear cylindrical heel portion 112 similar to the heel portionof the bullet 10 of FIG. 1. Heel portion 112 has a concave cavity 114 inits rear face 116. A step 118 leads to cylindrical central body portion120 and a step 122 leads to a tapering curved front portion 124. Portion124 is of a single curvature and ends in a flat nose 126. A centralcylindrical projection 128 extends forwardly from flat nose 126.

In FIG. 3 is shown a second bullet 200 of the invention.

Again this has a rear cylindrical heel portion 212 with a concave cavity214 in its rear face 216 and attached to a casing 232. A step 218 leadsto cylindrical central body portion 220 and a step 222 leads to atapering curved front portion 224. As with the bullet of FIG. 2, thefront portion 224 is of a single curvature and ends in a flat nose 226.A central cylindrical projection 228 extends forwardly from flat nose226.

In this embodiment the bullet 200 is shown after it has been coated withlubricant. As shown, a “reservoir” 230 of lubricant has collected andset around nose projection 228. This reservoir provides additionallubrication as it can be forced to flow along the exterior of the bulletas it is fired through a gun barrel.

In FIG. 4 is shown a third bullet 300 of the invention.

Again it has a rear heel portion 312 with a concave cavity 314 in itsrear face 316. A step 318 leads to cylindrical central body portion 320and a further step 322 leads to a tapering curved front portion 324.Portion 324 is again of a single curvature which ends in a flat nose326. Nose 326 has a centrally disposed cylindrical projection 328.

It will be appreciated that the embodiments shown and described aboveare for exemplification of the invention only. The dimensions and radiiindicated may be varied widely and may readily be adapted for bulletsother than .22 calibre.

The projections from the flat nose need not be cylindrical and may, forexample, as indicated above, be square in plan or domed.

The central body portion of the bullets will normally have conventionalknurled regions applied to them to provide the usual reservoirs forlubricant.

In FIG. 5 is illustrated an apparatus for the manufacture of a bullet ofthe invention.

The apparatus has a fixed die portion 400 defining a cylindricalmoulding cavity 402 in which is shown a plug 404 of lead to be formedinto a bullet of the invention. A first punch part 406 of cylindricalshape has an external diameter of size just to fit within cavity 402.Part 406 has a domed end 408 extending from an annular land 410, theland and domed end corresponding to the desired cavitied rear face of abullet. A second punch part 412 is also of cylindrical shape and ofexternal diameter just to fit into cavity 402 from the end opposite tothat into which part 406 is to be fitted. Part 412 has a central cavity414 of tapering curved shape corresponding to the desired curvature ofthe front portion of a bullet of the invention. At its innermost extentthe cavity 414 has a flat portion. 416 to correspond to the flat nose ofthe bullet and a cylindrical recess 418 centrally disposed in flatportion 416 to form the projection from the flat nose. A sprue hole 420leads from the recess 418 through the body of part 412 to vent toatmosphere.

When punch parts 406 and 412 are moved in the direction of arrows A andB respectively to enter cavity 402 of die 400, the lead plug 404 ismoulded to the desired novel bullet shape. The venting provided fromcavity 414 and recess 418 ensures that the lead can completely fillthose regions of punch part 412 to provide a satisfactorily formedshape.

1. An ammunition cartridge comprising a casing attached to a bullet, thebullet having a body portion of generally cylindrical shape, the bodyportion having a first end attached to the casing and a second endleading to a tapering curved portion terminating in a flat nose normalto a longitudinal axis of the bullet, the flat nose having acentrally-disposed projection extending forwardly away from the flatnose in the direction of the longitudinal axis, and a reservoir oflubricant provided externally of the bullet on an outer surface of theflat nose around the projection.
 2. An ammunition cartridge according toclaim 1, wherein the projection is uniformly disposed about thelongitudinal axis of the bullet.
 3. An ammunition cartridge according toclaim 1, wherein the projection is of circular shape in plan.
 4. Anammunition cartridge according to claim 3, wherein the projection is ofcylindrical shape.
 5. An ammunition cartridge according to claim 4,wherein the projection has a flat outer end.
 6. An ammunition cartridgeaccording to claim 4, wherein the projection has a domed outer end. 7.An ammunition cartridge according to claim 1, wherein a lubricantcoating is provided.
 8. An ammunition cartridge according to claim 1,wherein the ammunition cartridge is a .22 ammunition cartridge.
 9. Anammunition cartridge according to claim 1, wherein the tapering curvedportion is of constant radius.
 10. A method of manufacturing a bullethaving a longitudinal axis, the method comprising the steps of:providing material to form the bullet, shaping the material to form thebullet with a cylindrical body portion leading to a tapering curvedportion terminating in a flat nose at a front end of the bullet, and acentrally disposed projection extending forwardly away from the flatnose in the direction of the longitudinal axis of the bullet, andforming a reservoir of lubricant externally of the bullet on an outersurface of the nose around the projection.